1. Field of the Invention
The present invention relates to a frequency allocation method of a wireless communication system operating in frequency hopping mode and an apparatus therefor and, in particular, to a frequency allocation method and apparatus using a mirroring-assisted frequency hopping pattern for retransmission in a wireless communication system operating in frequency hopping mode.
2. Description of the Related Art
Universal Mobile Telecommunications System (UMTS) is one of the third generation (3G) mobile telecommunication technologies, which is evolved from Global System for Mobile communications (GSM) and General Packet Radio Services (GPRS) and uses Wideband Code Division Multiple Access (WCDMA).
The 3rd Generation Partnership Project (3GPP), which is responsible for the standardization of UMTS, is working on to significantly extend the performance of UMTS in the work item Long Term Evolution (LIE). LTE is a 3GPP standard that provides for a downlink speed of up to 300 Mbps and is expected to be commercially launched in 2010. In order to fulfill the requirements for the LTE systems, studies have been done in various aspects including minimization of the number of involved nodes in the connections and placing radio protocol as close as to the radio channels.
In the recent wireless communication systems, a mirroring technique is used for achieving frequency diversity gain to improve the reception reliability. As a representative example, Long Term Evolution (LIE) uses the mirroring technique for uplink transmission in frequency hopping mode. Particularly in Hybrid Automatic Repeat Request (HARQ) process, the LTE supports an inter-subframe frequency hopping with the mirroring technique for every initial transmission and retransmission to improve the reception reliability of the retransmitted data.
In the current standard specification, however, the HARQ retransmission is performed in unit of 8 subframes while a radio frame is composed of 10 subframes, and this difference diminishes further randomization of the frequency hopping even along with the mirroring technique, resulting in reduction of frequency diversity gain.